JGS1, JGS2 & JGS3 Quartz Glass

JGS1, JGS2 and JGS3 are useful purchasing categories for optical quartz glass, but the label alone does not define a finished optical component. The working wavelength and thickness must be stated because transmission changes with both material route and optical path length.

The JGS Name Does Not Define Optical Quality

The underlying classification also recognizes spectral, homogeneity, birefringence, striae, granular inhomogeneity, bubble and fluorescence levels. A commercial supplier may use the JGS label more loosely, so the RFQ should identify the measurable properties that matter to the finished part.

Finished Components and Fabrication

JGS materials can be cut, ground, drilled, CNC-machined and polished into windows, discs, plates, wafers, cells, tubes and custom optical parts. Material selection should be completed before final polishing because the clear aperture, orientation and inspection plan may depend on the parent blank.

For replacement optics, send the old drawing together with the operating wavelength and actual failure mode. This helps distinguish a material problem from coating damage, thermal stress, contamination or an incorrect mounting condition.

Data Qualification

The wavelength bands shown above follow the JC 185-81 category definitions. Actual cutoff, transmission, hydroxyl content and optical quality remain grade-, thickness- and lot-dependent. The approved drawing, sample data and supplier certificate take precedence.

Engineering Data

Material Route, OH Content and Working Band

Material route	Grade	Applicable band	OH content	Typical use
Synthetic hydrolysis-fused silica	JGS1	185–2500 nm	≈1000 ppm	Deep-UV optics and lithography
Flame-fused natural quartz	JGS2	220–2500 nm	120–260 ppm	UV-visible windows and instruments
Vacuum-fused quartz	Grade-specific	UV–near IR; confirm grade	<3 ppm	Semiconductor and lamp components
Vacuum-fused low-OH quartz	JGS3	260–3500 nm grade classification	≤10 ppm	IR observation and low-OH components
Electric-fused continuously drawn quartz	Grade-specific	UV cut-off depends on grade	5–150 ppm; heat-treatment dependent	Lamps, heaters and optical-fiber support parts

OH content is grade- and batch-dependent; the lot certificate governs acceptance. UV-end transmission is influenced by metallic impurities. The absorption peak near 2730 nm is governed by OH, which is why JGS1 deep-UV material and JGS3 low-OH IR material behave differently.

Engineering Data

Typical Physical Properties

Property	Transparent quartz glass	Opaque quartz glass
Density	2.2 × 10³ kg/m³	1.92–1.95 × 10³ kg/m³
Hardness	570–585 KHN100	—
Tensile strength	4.8–5.0 × 10⁷ Pa	—
Compressive strength	>1.1 × 10⁹ Pa	>1.0 × 10⁹ Pa
Linear expansion coefficient	5.5 × 10⁻⁷ /°C	5.4 × 10⁻⁷ /°C
Thermal conductivity	1.4 W/(m·°C)	—
Specific heat	660–680 J/(kg·°C)	640–650 J/(kg·°C)
Softening point	1630–1700 °C	1580–1600 °C
Annealing point	1180–1220 °C	1050–1100 °C
General continuous service guideline	≤1100 °C	≤1000 °C

Typical properties are reference data, not allowable assembly stresses. Transparent material short-term excursions may reach 1200 °C; sustained use follows the lower continuous-service guideline. Annealing and softening temperatures are material properties, not service ratings.

Engineering Data

Typical Transmission · 3 mm Thickness

Grade	200 nm	220 nm	240 nm	260 nm	280 nm	300 nm	400 nm	600 nm	1000 nm	2000 nm	2700 nm	3000 nm
JGS2 · flame-fused	45	70	75	86	90	91	92.5	93	93	93	30	85
JGS3 · low-OH vacuum-fused	40	65	70	85	90	91	92	93	93	93	90	91
JGS1 · synthetic	89	90	91	92	92	92	92	93	93	93	0	80

All entries are transmission %. These are typical 3 mm specimen data, not guaranteed minima or values for all thicknesses. The 2700 nm tabulated point is near the 2730 nm OH band: JGS1 is approximately 0%, while low-OH JGS3 is approximately 90%. Specify wavelength, path length, surface finish and minimum transmission for the delivered part.